# US 11,908,361 B2 · Display device and driving method therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,908,361 B2 - Document ID: US11908361B2 - Status: Granted - Kind: B2 - Application number: 18/030,283 - Filed: 2020-10-08 - Published: 2023-11-16 - Granted: 2024-02-20 - Earliest claimed: 2020-10-08 - Assignees: Sharp Kabushiki Kaisha - Applicants: Sharp Kabushiki Kaisha - Inventors: Hiroyuki Furukawa; Chie Toridono; Masafumi Ueno - Web page: https://patentgrep.com/patent/US11908361B2 ## CPC - G09G 3/006: {Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309)} - G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element - G09G 2300/0452: Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components - G09G 2300/0842: forming a memory circuit, e.g. a dynamic memory with one capacitor - G09G 2310/08: Details of timing specific for flat panels, other than clock recovery - G09G 2320/0233: Improving the luminance or brightness uniformity across the screen - G09G 2320/029: by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel - G09G 2320/045: Compensation of drifts in the characteristics of light emitting or modulating elements - G09G 2320/0626: for control of overall brightness - G09G 2330/08: Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared - G09G 2330/12: Test circuits or failure detection circuits included in a display system, as permanent part thereof - G09G 2360/16: Calculation or use of calculated indices related to luminance levels in display data - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) ## Abstract The display device is provided with a degree-of-degradation calculating circuit that determines a degree of degradation representing a level of degradation of a compensation-target circuit element included in each of K pixel circuits which are some or all of a plurality of pixel circuits; a variation coefficient calculating circuit that calculates, as a variation coefficient, a value depending on a deviation determined based on degrees of degradation of the K pixel circuits; a reference luminance setting circuit that sets, based on the variation coefficient, reference luminance for determining display luminance of each display element after degradation compensation; and a compensation computing circuit that compensates for degradation of the compensation-target circuit elements by correcting input video signals based on the reference luminance and the degree of degradation of each of the K pixel circuits, upon generating video signals to be supplied to the plurality of pixel circuits. ## Claims ### Claim 1 A display device including a plurality of pixel circuits each including a display element driven by current and a drive transistor for controlling current to be supplied to the display element, the display device comprising: a degree-of-degradation obtaining circuit configured to determine a degree of degradation representing a level of degradation of a compensation-target circuit element included in each of K pixel circuits, the compensation-target circuit element being at least one of the display element and the drive transistor, and the K pixel circuits being some or all of the plurality of pixel circuits; an index value calculating circuit configured to calculate, as an index value, a value depending on a deviation determined based on degrees of degradation of the K pixel circuits; a reference luminance setting circuit configured to set reference luminance based on the index value, the reference luminance being luminance used as a reference for determining display luminance of the display element after degradation compensation; and a compensation computing circuit configured to compensate for degradation of the compensation-target circuit elements by correcting input video signals based on the reference luminance and the degree of degradation of each of the K pixel circuits, upon generating video signals to be supplied to the plurality of pixel circuits. ### Claim 2 (depends on 1) The display device according to claim 1, wherein the index value calculated by the index value calculating circuit increases as the deviation determined based on the degrees of degradation of the K pixel circuits increases, and the reference luminance setting circuit sets the reference luminance to a smaller value as the index value increases. ### Claim 3 (depends on 1) The display device according to claim 1, wherein the index value calculated by the index value calculating circuit increases as the deviation determined based on the degrees of degradation of the K pixel circuits increases, and the reference luminance setting circuit determines average luminance of K display elements included in the K pixel circuits for a case in which the K display elements emit light based on a predetermined gradation value in a state in which degradation of the compensation-target circuit element is not compensated for, and sets the reference luminance to the average luminance when the index value is less than or equal to a threshold value prepared in advance, and sets the reference luminance to a value smaller than the average luminance when the index value is greater than the threshold value. ### Claim 4 (depends on 3) The display device according to claim 3, wherein the reference luminance setting circuit includes: a parameter holding unit configured to hold, as parameters, a value, on a horizontal axis, of a critical point on a graph and a slope between adjacent critical points on the graph, so that the graph can be obtained, the graph having a value that the index value can take as the horizontal axis and having a value that an adjustment factor for calculating the reference luminance can take as a vertical axis, and the graph representing a correspondence between the index value and the adjustment factor; an adjustment factor calculating unit configured to calculate the adjustment factor based on the parameters and the index value; an average luminance calculating unit configured to calculate the average luminance based on the degrees of degradation of the K pixel circuits; and a reference luminance calculating unit configured to calculate the reference luminance by multiplying the average luminance by the adjustment factor. ### Claim 5 (depends on 1) The display device according to claim 1, wherein the plurality of pixel circuits include pixel circuits for red, pixel circuits for green, and pixel circuits for blue, the index value calculating circuit calculates an index value common to all colors, as the index value, and the reference luminance setting circuit calculates, based on the index value, base reference luminance used as a base for calculating reference luminance for each color, and sets, based on the base reference luminance, the reference luminance depending on light-emission efficiency for each color. ### Claim 6 (depends on 5) The display device according to claim 5, wherein the index value calculated by the index value calculating circuit increases as the deviation determined based on the degrees of degradation of the K pixel circuits increases, and the reference luminance setting circuit sets the base reference luminance to a smaller value as the index value increases. ### Claim 7 (depends on 5) The display device according to claim 5, wherein the index value calculated by the index value calculating circuit increases as the deviation determined based on the degrees of degradation of the K pixel circuits increases, and the reference luminance setting circuit determines average luminance of K display elements included in the K pixel circuits for a case in which the K display elements emit light based on a predetermined gradation value in a state in which degradation of the compensation-target circuit element is not compensated for, and sets the base reference luminance to the average luminance when the index value is less than or equal to a threshold value prepared in advance, and sets the base reference luminance to a value smaller than the average luminance when the index value is greater than the threshold value. ### Claim 8 (depends on 7) The display device according to claim 7, wherein the reference luminance setting circuit includes: a parameter holding unit configured to hold, as parameters, a value, on a horizontal axis, of a critical point on a graph and a slope between adjacent critical points on the graph, so that the graph can be obtained, the graph having a value that the index value can take as the horizontal axis and having a value that an adjustment factor for calculating the reference luminance can take as a vertical axis, and the graph representing a correspondence between the index value and the adjustment factor; an adjustment factor calculating unit configured to calculate the adjustment factor based on the parameters and the index value; an average luminance calculating unit configured to calculate the average luminance based on the degrees of degradation of the K pixel circuits; and a reference luminance calculating unit configured to calculate the base reference luminance by multiplying the average luminance by the adjustment factor, and calculate the reference luminance for each color based on the base reference luminance. ### Claim 9 (depends on 8) The display device according to claim 8, wherein the K pixel circuits are the pixel circuits for green, and with the base reference luminance being reference luminance for green, the reference luminance calculating unit calculates, based on the base reference luminance, reference luminance for red and reference luminance for blue. ### Claim 10 (depends on 5) The display device according to claim 5, wherein the K pixel circuits include the pixel circuits for red, the pixel circuits for green, and the pixel circuits for blue. ### Claim 11 (depends on 5) The display device according to claim 5, wherein the K pixel circuits are the pixel circuits for green. ### Claim 12 (depends on 1) The display device according to claim 1, wherein the degree-of-degradation obtaining circuit includes: a current measuring circuit configured to measure, for each of the K pixel circuits, current flowing through the compensation-target circuit element under a predetermined condition; and a degree-of-degradation calculating circuit configured to calculate the degree of degradation based on the current measured by the current measuring circuit. ### Claim 13 A display device including a plurality of pixel circuits each including a display element driven by current and a drive transistor for controlling current to be supplied to the display element, the display device comprising: a degree-of-degradation obtaining circuit configured to determine a degree of degradation representing a level of degradation of a compensation-target circuit element included in each of K pixel circuits, the compensation-target circuit element being at least one of the display element and the drive transistor, and the K pixel circuits being some or all of the plurality of pixel circuits; an index value calculating circuit configured to calculate, as an index value, a value depending on a deviation determined based on degrees of degradation of the K pixel circuits; a reference current setting circuit configured to set a reference current corresponding to reference luminance based on the index value, the reference luminance being luminance used as a reference for determining display luminance of the display element after degradation compensation; and a compensation computing circuit configured to compensate for degradation of the compensation-target circuit elements by correcting input video signals based on the reference current and the degree of degradation of each of the K pixel circuits, upon generating video signals to be supplied to the plurality of pixel circuits. ### Claim 14 (depends on 13) The display device according to claim 13, wherein the index value calculated by the index value calculating circuit increases as the deviation determined based on the degrees of degradation of the K pixel circuits increases, and the reference current setting circuit determines average current corresponding to average luminance of K display elements included in the K pixel circuits for a case in which the K display elements emit light based on a predetermined gradation value in a state in which degradation of the compensation-target circuit element is not compensated for, and sets the reference current to the average current when the index value is less than or equal to a threshold value prepared in advance, and sets the reference current to a value smaller than the average current when the index value is greater than the threshold value. ### Claim 15 (depends on 14) The display device according to claim 14, wherein the reference current setting circuit includes: a parameter holding unit configured to hold, as parameters, a value, on a horizontal axis, of a critical point on a graph and a slope between adjacent critical points on the graph, so that the graph can be obtained, the graph having a value that the index value can take as the horizontal axis and having a value that an adjustment factor for calculating the reference current can take as a vertical axis, and the graph representing a correspondence between the index value and the adjustment factor; an adjustment factor calculating unit configured to calculate the adjustment factor based on the parameters and the index value; an average current calculating unit configured to calculate the average current based on the degrees of degradation of the K pixel circuits; and a reference current calculating unit configured to calculate the reference current by multiplying the average current by the adjustment factor. ### Claim 16 (depends on 13) The display device according to claim 13, wherein the plurality of pixel circuits include pixel circuits for red, pixel circuits for green, and pixel circuits for blue, the index value calculating circuit calculates an index value common to all colors, as the index value, and the reference current setting circuit calculates, based on the index value, base reference current used as a base for calculating reference current for each color, and sets, based on the base reference current, the reference current depending on light-emission efficiency for each color. ### Claim 17 (depends on 16) The display device according to claim 16, wherein the index value calculated by the index value calculating circuit increases as the deviation determined based on the degrees of degradation of the K pixel circuits increases, and the reference current setting circuit sets the base reference current to a smaller value as the index value increases. ### Claim 18 (depends on 16) The display device according to claim 16, wherein the index value calculated by the index value calculating circuit increases as the deviation determined based on the degrees of degradation of the K pixel circuits increases, and the reference current setting circuit determines average current corresponding to average luminance of K display elements included in the K pixel circuits for a case in which the K display elements emit light based on a predetermined gradation value in a state in which degradation of the compensation-target circuit element is not compensated for, and sets the base reference current to the average current when the index value is less than or equal to a threshold value prepared in advance, and sets the base reference current to a value smaller than the average current when the index value is greater than the threshold value. ### Claim 19 (depends on 18) The display device according to claim 18, wherein the reference current setting circuit includes: a parameter holding unit configured to hold, as parameters, a value, on a horizontal axis, of a critical point on a graph and a slope between adjacent critical points on the graph, so that the graph can be obtained, the graph having a value that the index value can take as the horizontal axis and having a value that an adjustment factor for calculating the base reference current can take as a vertical axis, and the graph representing a correspondence between the index value and the adjustment factor; an adjustment factor calculating unit configured to calculate the adjustment factor based on the parameters and the index value; an average current calculating unit configured to calculate the average current based on the degrees of degradation of the K pixel circuits; and a reference current calculating unit configured to calculate the base reference current by multiplying the average current by the adjustment factor, and calculate the reference current for each color based on the base reference current. ### Claim 20 (depends on 19) The display device according to claim 19, wherein the K pixel circuits are the pixel circuits for green, and with the base reference current being reference current for green, the reference current calculating unit calculates, based on the base reference current, reference current for red and reference current for blue.